U.S. application Ser. No. 702,542 entitled "Elimination of Field-Induced Instabilities in Electrooptic Modulators" and filed Feb. 19, 1985 by J. A. Agostinelli described improved light valve devices and device fabrication methods which employ a water impermeable barrier layer, on portions of PLZT modulator panels of devices, to significantly reduce light transmission nonuniformity. In general light valve devices of this kind employ an electroded PLZT modulator panel sandwiched between crossed polarizers and the panel is activated to operate in a quadratic Kerr cell mode. Thus the modulator panel comprises a plurality of electrodes formed on one major surface in a manner allowing selective application of discrete electric fields across respective pixel portions of the panel. When the field is present across a particular pixel portion it becomes birefringent and the polarization of light passing therethrough from the ingress polarizer is changed so as to pass through the egress polarizer. When a field is absent the modulator material remains isotropic so that egressing light is blocked by the egress polarizer.
The above cited Agostinelli application teaches that space charge induced nonuniformities of such light valve devices are increased by moisture around the modulator panel pixel portions. That disclosure teaches that such nonuniformities can be reduced by removing moisture from the modulator surface (e.g. by heating) and overcoating that surface with an electrically insulating, optically isotropic, water impermeable barrier layer (e.g. an acrylic coating).